Sensativity will help you understand how much power is necessary to achieve a certain decibel. If you start with a sub that has 87 db sensativity (at 1 watt/1 meter) then to double the sound, 90 db, you would need to double the power, 2 watts. Then to get to 93 db, you would need 4 watts, 96 needs 8 watts, 99 needs 16 watts, 102 needs 32, and you come up with 111 db with 256 watts. If you do the same thing with a sub with a sensativity of 85 db, you will see that the sub that can handle 1,000 watts will play to 115 db with 1004 watts. So, with a 3 db difference, the 1,000 watt sub potentially will play twice as loud. Now this is all on paper, enclosures, amplifier quality, and vehicle will all change these two aspects. the 93 db sub in a good ported box in the back of a tahoe will sound louder than the 85 db sub in a sealed box behind the seat of a pick-up. Hope this helped.
